Utils contents

Minkowski Functionals Module

picasso.utils.minkowskifunctionals.estimate_marchingsquare(data, threshold)

Estimate Minkowski functionals (\(V_0, V_1, V_2\)) at a given threshold on an image with the technique of Marching Squares, described in Mantz et al 2008.

Parameters

• data{array}

  2D image (rescaled to \([-1,1]\) )

• threshold: {float}

  threshold value to estimate Minkowski functionals

Returns

• f: {float}

  the value of \(V_0\)

• u:{float}

  the value of \(V_1\)

• chi:{float}

  the value of \(V_2\)

picasso.utils.minkowskifunctionals.get_functionals(im, nevals=32)

Estimate Minkowski functionals (\(V_0, V_1, V_2\)) on a set of thresholds.

Parameters

• data{array}

  2D image (rescaled to [-1,1] )

• nevals: {int}

  number of thresholds where to evaluate minkowski

Returns

• x: {array}

  array of thresholds

• f :{array}

  the value of \(V_0( x )\)

• u:{array}

  the value of \(V_1(x)\)

• chi:{array}

  the value of \(V_2(x)\)

Utilities Module

picasso.utils.utils.MinMaxRescale(x, a=0, b=1)

Performs a MinMax Rescaling on an array x to a generic range \([a,b]\).

picasso.utils.utils.StandardizeFeatures(x)

Standardizes an array x to have average 0, and std. deviation 1 .

picasso.utils.utils.f2h(flat, target_header, nside, coord_in='C')

Returns a HEALPIX map projected and the footprint of a flat one , given a WCS header, using reproject package

Parameters

• flat{2D array}

  flat map

• target_header:

  header defined from set_header()

• nside:{int}

  nside of output healpix map

picasso.utils.utils.h2f(hmap, target_header, coord_in='C')

Returns a target square submap from a projected HEALPIX map, given a WCS header, using reproject package

Parameters

• hmap{array}

  healpix map

• target_header:

  header defined from set_header()

picasso.utils.utils.rd2tp(ra, dec)

Convert ra,dec -> theta,phi

picasso.utils.utils.return_intersection(hist_test, hist_true)

Estimate the intersection between two histograms.

picasso.utils.utils.set_header(ra, dec, pixelsize, Npix=128)

Sets the WCS header needed to perform the projection with h2f() and f2h().

Parameters

• ra,dec{float}

  coordinates of the center of the patch

• pixelsize:{float}

  the size of the pixels of the reprojected flat map in units of deg/pixel

• Npix:{int}

  number of pixels in one side of the flat map

picasso.utils.utils.tp2rd(tht, phi)

Convert theta,phi -> ra,dec